Rootworm control delayed

Growers probably will have to wait until 2002 to plant corn hybrids with Monsanto's MaxGard built-in corn rootworm protection.

Monsanto had been preparing for a limited launch in 2001. But when the company pledged in late November that it will not introduce new modified crops until the U.S. and Japan approve them for use in food and feed, all bets were off.

Monsanto hopes to receive needed USDA, EPA and FDA approvals by this spring and expects Japanese regulators to decide on use of the hybrids in food and feed by harvest of this year. Given Monsanto's new strictures, the 2001 launch appears unlikely unless Japanese approvals come sooner than expected and U.S. regulatory approvals all happen on time.

"Because of our new commitment, we are less optimistic than we were about being able to introduce our corn rootworm product in 2001," says Brett Begemann, Monsanto vice president for North American markets.

Last fall, in preparation for a 2001 launch, winter seed production fields were planted in South America. Now the most likely scenario for this year is that the testing program will be expanded under an Experimental Use Permit, says Steve Rosenbloom, MaxGard marketing manager.

"There is a 99.9 percent chance that MaxGard won't be commercialized until 2002," he states.

MaxGard action. Monsanto tested MaxGard in small replicated trials and strip plots on about 1,500 acres across the Corn Belt in 2000. Growers who had a chance to see MaxGard in action were impressed, says John McFerson, MaxGard technical manager.

"We demonstrated that the MaxGard technology is significantly better than conventional corn rootworm treatments," McFerson claims. "And control is significantly more consistent because MaxGard is not affected by environmental conditions, such as being too wet or too dry, or degrading before corn rootworm larvae hatch."

MaxGard hybrids contain a Bt strain that is active primarily in the roots, so it controls only corn rootworm larvae. The Bt strain is different from strains in hybrids with built-in corn borer protection.

Because corn rootworms must feed on roots in order to be controlled, growers will notice some root feeding with MaxGard hybrids.

"With a moderate-to-heavy corn rootworm infestation, with MaxGard you see only small feeding scars on the outside of the roots where typically you see root pruning with insecticides," McFerson explains.

MaxGard does not control secondary pests, such as wireworm, so MaxGard hybrids will be paired with an insecticide seed treatment. Seed planted in 2001 will be treated with Gaucho. Monsanto also will be evaluating other seed treatments that could be available for use in 2002.

As with other seeds with built-in insect protection, planting MaxGard hybrids will require a refuge to manage the development of resistant insects. The size and location of refuges are under discussion with EPA, McFerson says.

Availability. Whether the launch year is 2001 or 2002, seed will be available initially from at least 150 seed companies, including Dekalb and Asgrow, Rosenbloom says.

"The product offering across the Corn Belt will be fairly significant, mostly in the 95- to 120-day relative maturity range," he adds.

Several major seed companies have not signed on to develop MaxGard hybrids, including Novartis Seeds and Pioneer Hi-Bred International. Pioneer is expected to introduce its own corn rootworm resistance technology, developed in conjunction with Mycogen Seeds/Dow AgroSciences, in two or three years (see "New corn rootworm control," September 2000 for details).